1. Field of the Invention
The present invention is related to the field of signal transmission.
2. Related Art
As a result of recent developments in digital signal processing technologies, the use of digital interfaces is now becoming a major trend in signal transmission. Standards for digital interfaces, such as IEEE1394, allow various formatted digital signals to be transmitted through a single digital interface.
More specifically, using the IEEE1394 digital interface, digital audio/video devices are connected with each other to form a network of the devices. Digitized audio/video signals are mostly coded or compressed into particular formats, and then transmitted through the digital interface. Such a digital interface allows the digital signals, no matter what format they are in, to be transmitted within the network, and does not regulate or control the transmission path through which the digital signals are being transmitted.
In order to accomplish signal transmission between two devices in a network, one of which transmits a digital signal and the other of which receives the digital signal, the receiving device must be capable of decoding the signal transmitted in a particular format. In other words, both the transmitting and receiving devices have to have a common feature with regard to their coding/decoding capabilities.
It could have been relatively easy to fulfill this requirement when digital signals were coded and transmitted in limited number of formats such as the Digital Video (DV) format. The situation has changed, however. Various types of compression techniques, including Digital Video Interactive (DVI) and Motion Picture Experts Group (MPEG) compression, have been developed and used to achieve higher performance of digital signal transmission. In addition, some of these formats have distinctive modes, such as High Definition (HD) and Standard Definition (SD) modes of MPEG2, in terms of the transmission speed and bandwidth of the signal.
In theory, if every device in a network were to have a common feature with regard to their coding/decoding capabilities, digital signals would be transmitted between the devices through the IEEE1394 digital interface. In practice, however, each device has limited coding/decoding capabilities. As a result, the coding/decoding capabilities of the transmitting and receiving devices may not necessarily correspond to each other.
When such a discrepancy in digital signal formats occurs, it is possible to accomplish signal transmission between the devices in the network by
using a converter which converts a digital signal format into another format that the receiving device can cope with; or
decoding a digital signal into analog so that the signal is supplied in an analog format.
To do so, a transmission path in the network has to be reestablished so that it involves an appropriate decoder or converter. It is, however, a complicated task to reestablish a pertinent transmission path taking into account both the format of the signal that a transmitting device provides and the various capabilities of the devices.
Furthermore, an analog interface has to be used to transmit a signal in an analog format; otherwise the analog signal cannot be transmitted successfully. In other words, a determination needs to be made as to which interface is to be used, digital or analog, depending upon the format of the signal transmitted through the interface.
For the foregoing reasons, there is a need for a method and apparatus for determining a transmission path between a transmitting device and a receiving device based on the capabilities of the devices within a network.
A method includes integrating information regarding receiving, transmitting and converting capabilities of each device in a network with regard to signal formats, so that a pertinent transmission path can be determined. More specifically, the method includes collecting information regarding what formats each of the devices in the network is capable of receiving, transmitting and converting, and producing possible transmission paths between a receiving device and the other devices based on the capability information collected. Such possible transmission paths can be specified in terms of the order of devices involved in the transmission paths and a signal format between these devices involved. Once a transmitting device and a format of a transmitted signal have been identified, one of the possible transmission paths that matches the transmitting device and the transmitted signal format is selected as a pertinent transmission path.
Capability information may be disposed in each of the devices in the network, and the devices may communicate with each other to collect the capability information through a digital interface, such as an IEEE1394 interface.
Also, the method may display the selected transmission path on a monitor, so as to assist a user to manually establish a pertinent transmission path within the network.
According to one aspect of the invention, an apparatus includes a memory for storing information regarding receiving, transmitting and converting capabilities to signal formats. Also included is a memory for storing capability information of other devices. An analog input terminal and a digital input/output terminal coupled to the memory is included. A decoder coupled to the digital input/output interface is included. A controller which refers to contents in the memory for storing information regarding receiving, transmitting and converting capabilities to signal formats and the memory for storing capability information of other devices to produce possible transmission paths based on the capability information stored is included. Also, selection of either the output of the decoder or the analog terminal is provided. A monitor for displaying a selected path to a user may also be included.